It is well known that tetrahydrofuran can be produced by a series of reactions starting with the reaction of aqueous formaldehyde and acetylene in the presence of a catalyst, i.e., copper acetylide complex, to form butynediol. Butynediol is then reduced by hydrogenation to butanediol. Butanediol is cyclized in the presence of sulfuric acid to tetrahydrofuran.
Some commercial processes for the synthesis of butynediol (see U.S. Pat. No. 3,560,576) operate with excess formaldehyde, thereby improving yields. However, as formaldehyde inhibits the reduction of BYD in the hydrogenation step, it is necessary to remove formaldehyde from butynediol. Generally, the crude butynediol is distilled to remove formaldehyde which is recycled in the system. This distillation step is expensive both in the initial cost of equipment and in energy consumption during use.